DE 30 24 169 describes a method for operating a photocoagulator for biological tissue.
DE 39 36 716 describes a device for the thermal changes of biological tissue.
However, the devices described in both publications are disadvantageous in that tissue worthy of preservation is destroyed during their application (particularly, the photoreceptor layer located in beam direction in front of the retinal pigment epithelium). Therefore, the task of providing a coagulation system for the coagulation of organic tissues that minimizes the destruction of tissue worthy of preservation has already been considered in the past, whereby the local treatment is terminated once a defined temperature is reached at the coagulation point.
DE 101 359 44 is an example thereto. Therein, a temperature-controlled coagulation system for the coagulation of organic tissues, particularly the retina, is described which comprises a continuous coagulation laser and a pulsed measuring laser, a detector, a control device, and an interrupter, whereby the coagulation laser is designed to emit a coagulation beam and the measuring laser is designed to generate in the target area of the coagulation laser a temperature-dependent measurement signal for the detector; whereby the detector exhibits a temperature sensor, which evaluates the effect of the applied radiation, and which is designed to detect a signal and to transmit the detection of a signal to the control device; wherein the control device is designed to activate an interrupter; whereby the interrupter is designed to interrupt the emission of waves with a wavelength at least that of the working beam of the laser; and whereby the signal corresponds to a degree of coagulation and/or the temperature of the tissue.
Said solution for a temperature-controlled laser photocoagulation is disadvantageous because only one temperature measuring system capable of controlling the integral temperature profile within a coagulation spot during a laser coagulation can be provided, and measurement signals are only obtained when there is contact with the eye.
In DE 103 01 416 B1, the entire content of which is incorporated by reference, a device and a method for non-contact temperature control and adjustment is described, by a temperature change is to be determined interferometrically at the coagulation spot. Thereby, said document proceeds on the assumption that through the temperature change a refractive index change occurs in a defined volume which is subsequently determined interferometrically. However, as already described therein, such effect is very low since the temperature-induced change of the refractive index and the expansion of the measurement volume partially cancel each other out. OCT (optical coherence tomography) is also mentioned in said document as a method of analysis.